As a vehicle seat, there has been proposed a vehicle seat in which a metal-made round shaft is employed as a rear frame section of a seat cushion frame for the seat, zigzag springs for supporting a cushion thereon are stretched between the round shaft and a forward frame section of the seat cushion frame, and end portions of the zigzag springs are fixed to the round shaft by a retainer (Japanese Patent Application Laid-Open No. 2006-14867).
The retainer comprises a longitudinal body of a substantially U-shape in cross-section, and pairs of first and second spring engagement pieces provided at both longitudinal edges of the longitudinal body so as to be spaced apart from one another along the longitudinal edges, the first spring engagement pieces being bent laterally outwardly from one of the longitudinal edges of the longitudinal body and the second spring engagement pieces being bent laterally outwardly from the other of the longitudinal edges of the longitudinal body. The longitudinal body and the pairs of first and second spring engagement pieces are integrally formed from a metal plate by causing the metal plate to be bent. The retainer is adapted to be mounted on the round shaft with the substantially U-shaped longitudinal body being fitted over the round shaft, with the first spring engagement pieces being located inside the seat cushion frame, and with the second spring engagement pieces being located outside the seat cushion frame. Each of the end portions of the springs is formed substantially in a U-shape in outline and comprises first and second spaced apart axial regions and an intermediate axial region interconnecting the first and second spaced apart axial regions. The end portion of a spring is fixed to the round shaft through the retainer, with the first axial region and the second axial region being heldly engaged with a corresponding first spring engagement piece and a corresponding second spring engagement piece of the retainer, respectively, and with the intermediate axial region being located under the round shaft and engaged with the round shaft.
An inner circumference of the substantially U-shaped longitudinal body of the retainer is dimensioned such that the longitudinal body can be fitted over an outer circumference of the round shaft. Therefore, when the zigzag springs are fixed at the end portions thereof to round shafts having various diameters, for example, about 22.2 mm or 23.8 mm, retainers whose substantially U-shaped longitudinal bodies have inner circumferential sizes that allow the retainers to be fitted over outer circumferences of the round shafts are required to be prepared for the round shafts having various diameters. Moreover, when the retainer which is formed of metal material is directly fitted over the metal-made round shaft, there is a possibility that noise will be produced by rubbing the metal-made retainer with the metal-made round shaft. In order to prevent the production of the noise, application of a resin coating onto the retainer is required, thus resulting in increased cost of the retainer.